Boiler Leaking Water: Quick Fixes and Prevention Tips

James Elston
Written by James Elston
Updated on 8th April 2024
Posted on 7th April 2024
Topic: Boiler Guides
Boiler Leaking Water Cause And How to Fix a Boiler Leak Guide

Is your boiler leaking water?

This urgent problem not only disrupts the comfort of your home but can also signal underlying issues that if left unaddressed, lead to more extensive damage.

In this article, we’ll dive straight into identifying common causes of boiler leaks, provide steps for immediate action, and discuss when to call in the professionals for a precise fix or replace a boiler.

From corrosion to faulty components, we explain the ins and outs of boiler water leaks and give you preventative tips to help avoid future issues.

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Leaking Water From Boiler Overview

  • Water leaking from a boiler can be caused by corrosion, wear and tear, high pressure, or a faulty heat exchanger, and ignoring them can lead to serious safety risks, necessitating immediate professional attention.
  • Immediate responses to a leaking boiler include turning off the water supply, collecting leaking water, drying the area, and contacting a Gas Safe registered engineer; also, routine safety precautions are essential in case of potential gas leaks.
  • Prevention of future boiler leaks involves regular maintenance and annual boiler servicing by a Gas Safe engineer, installing protective devices like magnetic filters to capture debris, and ensuring boiler pressure is within safe limits.

Boiler Leaks: Causes and Dangers

Boiler water leaks are typically caused by:

gas safe
  • Corrosion
  • Wear and tear
  • High boiler pressure
  • A faulty heat exchanger

Corroded or ill-fitting pipes are frequent culprits of a leaky boiler, and leaks can also arise from loose joints in the heating system, which are subject to expansion and contraction.

Ignoring boiler leaks can pose serious risks, reinforcing the need for immediate attention to the problem.

A leaking boiler dangerous situation may arise, especially in cases of serious faults, requiring urgent repair by a certified Gas Safe engineer. Prompt intervention is critical to prevent exacerbation of issues resulting from a boiler leak.

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Corrosion and wear


Corrosion can cause the following issues in a boiler system:

  • Rust and debris build-up
  • Breaking of rubber seals
  • Water leaks
  • Corrosion of pipes and components, leading to small holes and leaks.

Wear and tear from repeated expansion and contraction of water can cause joints and pipe connections to become loose in a heating system.

Using a chemical flush can help reduce the accumulation of limescale and debris within the boiler’s pipes, which in turn minimises the risk of boiler corrosion and subsequent leaks.

High boiler pressure

High boiler pressure can cause water to leak from the boiler and lead to damage to the system’s components. To determine if boiler pressure is too high, check the pressure gauge; a reading in the red zone indicates excessive pressure, while the ideal pressure is around 1 bar within the green markings.

If the boiler pressure is too high, follow these steps:

pressure gauge
  1. Turn off the heating.
  2. Allow the radiators to cool.
  3. Secure the filling loop valves.
  4. Bleed the radiators to release the excess water.

When a boiler is leaking due to high pressure, inspect the pressure relief valve and consider releasing some water from the system to reduce pressure if necessary.

If your boiler is leaking water, this could also be a sign of a more serious issue that requires professional attention.

Faulty heat exchanger

Heat exchangers can leak due to corrosion, decay over time, or damage from being over-pressurised. Lower-quality boiler models are particularly susceptible to heat exchanger failure, which may crack, become damaged, and leak.

The heat exchanger is one of the most expensive boiler components, making its failure a significant cost concern. Gas Safe engineers are qualified to replace faulty heat exchangers, providing a professional solution to this issue.

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Immediate Actions for a Leaking Boiler

In the event of a boiler leak, you should immediately switch off the water supply and central heating, place buckets under the leaks, and dry any water spills.

question mark

After taking immediate measures, you should check for any visible signs of corrosion or rust in the pipework.

Contact a qualified professional to check the severity of the boiler leak. If water is leaking from the pressure relief valve, call a Gas Safe registered engineer.

If you can’t immediately identify the cause of the leak, turn off the water and contact a local Gas Safe Engineer without delay.

Safety precautions

If you suspect a gas leakage from the boiler, call the National Gas Emergency Service immediately on 0800 111 999. In the event of a boiler leaking oil, shut off the oil supply, ventilate the area by opening windows, and contact a heating engineer or your home insurer’s emergency service.

If a gas leak is detected, open all windows and doors to dissipate the gas, avoiding potential gas buildup. Do not continue to use a boiler that is leaking water, as it can cause further damage and create safety hazards.

Temporary fixes

If you see water leaking from a pipe joint, follow these steps:

  1. Dry off the affected area with a cloth.
  2. Attempt to carefully tighten the joint to reduce or temporarily stop the leak.
  3. While waiting for a professional to address the leak, place a container or bucket underneath the dripping water to prevent damage to the surrounding area.

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Calling an Engineer for Boiler Leaks

Enlisting a Gas Safe Registered engineer is crucial for boiler repairs as DIY attempts can be hazardous due to the dangers of working with gas.

Gas Safe engineers are certified professionals specialising in the maintenance, repair, and safety checks of gas appliances and systems, including boilers.

Registered engineers are vital for ensuring gas appliances like boilers meet legal safety standards and are properly maintained to prevent hazards. For professional expertise and safety, a registered Gas Safe engineer should be called to fix a boiler leak.

Repairing corroded pipes

Corroded pipes are a common cause of boiler leaks and must be replaced to ensure the system’s integrity. A Gas Safe engineer will replace a single corroded pipe to remedy the problem and prevent further leaking.

If corrosion has occurred in just one part of the heating system, that specific part requires replacement to restore proper function.

Replacing faulty heat exchangers

Replacing a faulty heat exchanger is a process that a professional engineer will undertake when it is deemed more cost-effective than repairing. When the boiler is no longer under warranty and the costs for repair are high, it is often more economical to opt for replacement of the heat exchanger.

Adjusting boiler pressure

As with low boiler pressure, high boiler is an issue you can fix yourself by bleeding radiators. If you are unsure however, a Gas Safe engineer ensures that boiler pressure is maintained within its optimum range to enhance performance and prevent leaks.

Adjusting boiler pressure can involve a variety of methods such as bleeding radiators or using the drain-off valve.

Techniques for adjusting boiler pressure include opening the filling loop to add water, adjusting the pressure relief valve, or bleeding excess air from radiators.

Regularly monitoring the boiler pressure and engaging a Gas Safe engineer for maintenance can help in keeping the pressure within the safe range, thereby preventing potential leaks.

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Preventing Future Boiler Leaks

Annual servicing of a boiler ensures that minor issues can be identified and addressed before they escalate into more significant problems, potentially averting future leaks.

Regularly checking the boiler helps in monitoring its health and timely intervention if any discrepancy is found.

Having a new boiler cover plan may be cost-effective as it can include annual servicing and regular checks for your central heating system, thus assisting in leak prevention.

Regular maintenance

Regular maintenance and annual check-ups of a boiler are crucial in identifying minor issues early which helps in preventing larger, more costly problems. A typical annual boiler service performed by a Gas Safe engineer includes:

  • Visual inspection
  • Flue check
  • Internal component cleaning
  • Diagnostics to ensure safe and proper operation.

Service duration for a boiler can differ with newer models possibly requiring as little as 30 minutes and older or more complex models taking an hour or more. While boiler servicing is not legally required for homeowners, landlords must conduct annual gas safety checks on boilers within their rental properties.

Installing a magnetic filter

A magnetic filter can assist in preventing boiler leaks by:

  • Attracting and capturing magnetic particles from the heating system
  • Trapping metallic debris from the water circulating through the heating system
  • Preventing blockages
  • Maintaining system efficiency.

A magnetic filter in a boiler system can trap iron oxide particles, reducing corrosion and enhancing the boiler’s longevity.

Monitoring boiler pressure

Regularly checking the boiler pressure gauge is crucial for preventing leaks and ensuring the boiler operates within safe parameters.

Monitoring the correct boiler pressure involves checking the pressure gauge regularly to ensure the pressure is within the manufacturer’s prescribed safe range, which is essential for identifying early signs of leaks or pressure-related issues.

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Choosing a Reliable Boiler Brand

Selecting the most reliable boiler or brand is crucial to ensure long-term efficiency, reliability, and heating performance in the home. Top boiler brands include:

  • Viessmann
  • Alpha
  • Ideal
  • Worcester Bosch

These brands are recognised for their efficiency and reliability, underpinned by advanced technology and high customer satisfaction.

Energy efficiency ratings

A boiler’s energy efficiency rating is crucial for determining potential running costs and how much each model could save on energy bills. The SEDBUK rating helps homeowners compare boilers with a detailed efficiency percentage between 70-92%.

Modern condensing boilers are typically rated A according to ErP standards, but SEDBUK percentages provide a more distinct efficiency comparison. Since April 2018, ‘Boiler Plus’ legislation has required all gas boilers in England to have a minimum of 92% efficiency (ErP).

Warranty coverage

Maintaining a manufacturer’s warranty often necessitates the completion of an annual boiler service. The cost of a boiler service is around £100, and the annual service must be documented by a certified Gas Safe engineer to satisfy boiler warranty requirements.

Adhering to these maintenance requirements is essential for ensuring long-lasting protection under the warranty. By complying with warranty stipulations, homeowners can enjoy peace of mind knowing their boiler is protected.

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In conclusion, understanding the causes and dangers of boiler leaks is essential to taking immediate actions and seeking professional solutions.

By regularly monitoring boiler pressure, performing annual maintenance, and choosing a reliable boiler brand, you can effectively prevent future boiler leaks.

Remember, while temporary fixes might help, professional intervention is crucial to ensure safety and efficiency. Engage the services of a Gas Safe engineer for repairs and maintenance, and enjoy peace of mind knowing your boiler is in safe hands.

Frequently Asked Questions

Can I still use my boiler if its leaking?

No, you should not use your boiler if it’s leaking. Turn off the water supply and central heating, place buckets under the leaks, and dry any water spills. If it’s a gas leak, turn off your gas supply.

Why is my boiler leaking water from underneath?

Your boiler may be leaking water from underneath due to pressure issues, loose joints, or cracks. To address this, consider calling in a professional to accurately diagnose and fix the problem.

What are the common causes of boiler leaks?

Boiler leaks are commonly caused by corrosion, wear and tear, high boiler pressure, or a faulty heat exchanger. Be sure to address these issues promptly to prevent further damage.

What immediate actions should I take if my boiler is leaking?

Immediately switch off the water supply and central heating, place buckets under the leaks, and dry any water spills. Then, contact a professional to assess the severity of the leak.

What are the professional solutions to boiler leaks?

The professional solutions to boiler leaks include repairing corroded pipes, replacing faulty heat exchangers, and adjusting boiler pressure. It’s crucial to always call a Gas Safe registered engineer for these tasks.

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Written by
James Elston
James Elston Director Of Boiler Central
Posted on: 7th April 2024
Topic: Boiler Guides

James Elston is our resident boiler replacement and heating expert here at Boiler Central. With over 20 years experience in the boiler installation industry, James ensures that he knows everything there is about our Gas Safe boiler installations, energy saving and home heating solutions. This can be from simply procuring the latest best combi boilers, to reviewing and ensuring that Boiler Central maintains the highest standards across our boiler installation company.

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